17 February 2016

On a European level, a list of invasive alien species of EU concern that cannot be traded, kept, or bred and of which the future dispersal should be limited through preventive actions (e.g. pathway regulation) or active management has recently been approved. Chinese mitten crab and five species of crayfish (O. limosus, O. virilis, P. leniusculus, P. clarkia and Procambarus fallax f. virginalis) are on the list of EU concern and therefore regulated.

Update, 19 February 2016: Emailing the authors got me a link to this page (in Dutch). And indeed, “invasive crayfish,” including Marmorkrebs, are definitely listed, with an identification sheet to help non-specialists tell the invasive from the natives. I was still curious about the actual legislation, however. It appears to have come into effect 2 January 2016. Using Google translate on this page, I learned:

There is currently a significant difference in policies implemented by the Member States of the European Union, which measures are often too fragmented to lead to effective results. So it makes little sense that one country by conducting a thorough control of some invasive species, if the neighbors do not. To arrive at a more unified and effective approach was therefore defined by the European regulation.

Indeed, the variation in legislation is one part of the problem I’ve written about. But what’s the rule for Marmorkrebs pet owners

There is a total ban on the possession, trade, transport, production and release of these species in the wild.Pet animals which were the entry into force of the Regulation in possession may be held until natural death, provided that the animals are kept in a closed environment, can not escape and can not reproduce. Kind used for the sake of commercial purposes, can be kept for two years after the inclusion of the species on the list under similar conditions.

The “cannot reproduce” clause is... um... problematic for Marmorkrebs owners. They all reproduce! So it’s not clear to me if this means that pet Marmorkrebs people have now are grandfathered in or not. I suspect not.

The penalties will be set by the individual member states.

As the saying goes, “Big if true.” This appears to be a major step towards limiting the spread and ownership of Marmorkrebs in the pet trade in Europe.

This would be a perfect time to start doing research on the availability of crayfish in the pet trade. If the legislation is effective, crayfish availability should decline over the next couple of years. As far as I know, only one paper has tried to systematically examine the effect of legislation on the trade in crayfish: Magalhães and Andrade (2015) found a decrease, but not the elimination, of crayfish in the pet trade, and concluded the ban was not effective.

13 February 2016

In the present study, we performed behavioral analyses of the habituation of backward escape swimming in the marbled crayfish, Procambarus fallax. Application of rapid mechanical stimulation to the rostrum elicited backward swimming following rapid abdominal flexion of crayfish. Response latency was very short—tens of msec—suggesting that backward swimming is mediated by MG neurons. When stimulation was repeated with 10 sec interstimulus intervals the MG-like tailflip did not occur, as the animals showed habituation. Retention of habituation was rather short, with most animals recovering from habituation within 10 min. Previous experience of habituation was remembered and animals habituated faster during a second series of experiments with similar repetitive stimuli. About half the number of stimulus trials was necessary to habituate in the second test compared to the first test. This promotion of habituation was observed in animals with delay periods of rest within 60 min following the first habituation. After 90 min of rest from the first habitation, animals showed a similar time course for the second habituation. With five stimuli at 15 min interval during 90 min of the rest, trained animals showed rapid habituation, indicating reinforcement of the memory of previous experiments. Crayfish also showed dishabituation when mechanical stimulation was applied to the tail following habituation.

09 February 2016

A couple of years ago, some fun dialect maps were making the rounds on the Internet, which I blogged about because one of the questions was about what people call freshwater crustaceans that look like small lobsters.

Those maps were based on the Harvard dialect survey, which ended 2003. This is now being followed by the Cambridge dialect survey, which started 2007, and what people call Astacidea is again one of the questions.

The map is interesting to check out. I think “lobster” looks far more common in the map than in the data, probably because of the layering of the data points.

Interestingly, the gap in use between “crayfish” and “crawfish” widened between the Harvard and Cambridge surveys. But in both surveys, “crayfish” is more northeast, “crawdad” is midwestern, and “crawfish” is southern. I wonder how “fish” metamorphosed into “dad” in the central U.S.

02 February 2016

The world hotspot for crayfish species, by a long, long way, is the southeastern United States (map from Richman et al. 2015).

The southeastern U.S. is also notable for relatively large populations of African-Americans.

You might think that given the overlap in these two maps, that there would be expertise in the African-American community about crayfish. But I am struggling to think of any African-American scientist who has studied crayfish. Who am I missing?

This also points to crayfish being a great entry point to introduce African-Americans to topics like biology and conservation.

01 February 2016

The Marmorkrebs.org home page has migrated over to a new institutional server. The old site will be up for a while until I get a redirect notice up, but it will eventually close as website support for my previous institution (The University of Texas-Pan American) transitions to my new one (The University of Texas Rio Grande Valley).

If you visit the site by a directly typing in the URL into a browser, you should see no difference.

If you bookmarked the homepage, take a moment to check that it directs to the correct URL: